Why this is a safety decision

Regulation 12 of the Workplace (Health, Safety and Welfare) Regulations 1992 requires every floor in a workplace, and the surface of every traffic route, to be of a construction suitable for the purpose it is used for. It must have no hole, slope, unevenness or slipperiness that puts anyone’s health or safety at risk, and effective drainage where that is needed. You can read regulation 12 in full at legislation.gov.uk. That duty falls on the business in control of the workplace, which is why the specification is worth getting right rather than leaving it to whatever the supplier has in stock.

The part most people get backwards

HSE publishes a case study, Caution! Wet paint!, about a Midlands warehousing company that repainted the floor markings separating pedestrians from vehicles at its goods access point. The area was not barriered off, the shutter door was not closed and no wet paint signs were put out. An employee whose usual entrance was blocked used the vehicle entrance instead, slipped on the wet paint and broke her wrist. The local authority inspector described the accident as completely preventable, and the company paid over £10,000 in fines and costs.

Wet paint is the obvious hazard. HSE makes a second and more useful point. Paint can leave a very smooth surface with very low microroughness, so once dust or moisture is present, carried in on shoes or from wet tyres, the dried painted floor can be considerably more slippery than the one it replaced.

The slip resistance figures worth knowing

HSE’s information sheet Assessing the slip resistance of flooring (GEIS2) sets out how flooring is measured. Two sets of figures are worth having in front of you when a supplier hands over a data sheet. You can read the full information sheet on the HSE website.

That table is based on the UK Slip Resistance Group guidelines published in 2011. The question to ask a supplier is what the value is in the contaminated condition that matches your site, not in a dry laboratory condition.

The second measure is surface roughness, written as Rz and given in micrometres. HSE states that it gives a good indication of floor slipperiness in water-contaminated conditions.

What the substrate decides

Most floor coating failures are substrate failures. The coating gets blamed, but the slab was never ready for it.

• Moisture. Concrete holds water, and coating a slab that is still releasing it causes blistering and loss of adhesion. Moisture is established by measuring against a recognised method, not by judging how the slab looks. No single threshold applies to every product, so the figure to work to is the one in the technical data sheet for the system being used. Where a slab has no effective damp proof membrane beneath it, a surface coating is not the answer on its own.
• Contamination. Old coatings, curing compounds, oil, grease and tyre marks all stop a new system bonding, and oil soaks into concrete and travels back out through fresh coating. Degreasing comes before preparation, not after it.
• Preparation. Concrete needs mechanical preparation so the coating can key into it, usually by diamond grinding, shot blasting or scarifying. Acid etching is the weakest option and is generally unsuitable for a hard-wearing industrial system. A system applied over a polished, power-floated slab has nothing to key into, and product quality does not compensate for that.

Coating types

Treat that as a starting point rather than a specification. Performance figures, recoat windows, temperature limits and the slip resistance value in your own contaminated condition all come from the manufacturer’s data sheet for the system being quoted.

Line marking and working in a live building

Floor markings are how a building separates people from vehicles, and the HSE case above began with a company repainting exactly those. Specify markings with at least the slip resistance of the floor around them, because a smooth painted line across a walking route is a hazard in its own right.

Scheduling, phasing and out-of-hours working are covered in our guide to minimising downtime for offices and schools, and the same principles apply on an industrial site. Two things are specific to floors. Touch dry and ready for traffic are not the same, and foot traffic, pallet trucks and forklifts each have their own return point set by the data sheet. And the area being coated has to be barriered and signed with a genuinely usable alternative route, which is precisely what went wrong in the HSE case.

For an example on a live site, see our Leicester warehouse redecoration case study, where concrete flooring that had lost its protective seal was recoated with an anti-slip finish while the facility stayed in use.

Common mistakes

When to bring in a contractor

Small areas of light-duty floor are within reach of an in-house team with the right preparation equipment. It stops being sensible when the area carries forklift or heavy plant traffic, when the floor gets wet, oily or greasy in use, when the slab is contaminated or previously coated, when the building has to stay open, or when pedestrian and vehicle routes are being marked or changed.

It is reasonable to ask any contractor quoting for the work how they will prepare the slab, what moisture reading they will work to, and what slip resistance value the finished floor is expected to achieve in the condition your site actually runs in.

Arrange a site survey

For wall, door and trim finishes in the same buildings, see our guide to the best paint finishes for high-traffic commercial areas, or browse our commercial painting and decorating services.